Class C Motorhomes
Class C Motorhome power systems are built with the following considerations:
Moderate roof space allows for a couple of large panels.
The potential for high current alternator charging.
Heavy loads like air conditioners requiring large battery systems and inverter/chargers.
Battery capacity limited by what fits under the step, unless a storage bay can be sacrificed.
The step-by-step guide below takes you through the myriad of options and design considerations for developing a custom power system.
Custom Configuration
1. Select a battery bank: The battery bank is the heart of the system. We recommend LifeBlue lithium batteries because of their ease of installation, high quality, and ability to expand over time. We typically recommend installing Lithium batteries in weatherized and ideally insolated compartments. This means that most step-bay are not recommended for lithium, and adjacent side bays or interior compartments are necessary. Additional battery bank options that will fit under the step include Lifeline AGM Dual 6V 220Ah batteries.
We sell LifeBlue batteries as a base kit, which includes one battery, a Victron BMV-712 battery monitor, cable, lugs, and heat shrink, plus expansion kits, which include one battery and parallel cables. For two batteries, select one base kit and one expansion kit. If you want three batteries, get one base kit and two expansion kits.
LifeBlue batteries come in three size configurations, choose what will fit best for your application.
100Ah: H 9.4" x W 12.5" x D 6.5" 28lbs
200Ah: H 10.8" x W 20" x D 6.9" 57lbs
300Ah: H 9.5" x W 20.25" x D 11" 83lbs
If your plan is to run an air conditioner, you will get about 1 hour of runtime on a 15,000BTU A/C running at full per every 200Ah of lithium battery capacity. You will also need at least a 3000VA Inverter, an Easy Start Kit, and three LifeBlue batteries, which means relocating the battery bank to a bay or inside.
Do not let your lithium batteries get below -10° F. Lithium batteries will not charge below 32° F.
Estimated Installation Labor
200Ah LifeBlue Lithium System with BMV-712
10 hours / $1,450
This is a complete LifeBlue lithium RV battery base kit with a Victron BMV-712 Bluetooth battery monitor. The monitor is included to provide cumulative battery bank data, compatible with Victron VRM monitoring. When expanding the battery bank, do not mix battery models and limit the battery bank to four batteries.
This kit is designed to be an add-on to an existing LifeBlue battery system.
Other battery bank options:
2. Alternator Charging: When upgrading to lithium batteries you will need to upgrade your battery combiner for alternator charging. Without this modification, the higher resting voltage of a lithium battery will trick the existing battery combiner relay into thinking the alternator is running and the lithium battery bank will be paralleled to the starter battery, even when the ignition is turned off. The result is lithium batteries draining into the starter battery until they crash to a dangerously low voltage or the lithium batteries’ internal BMS engages, preventing further discharge.
If you have a battery bank consisting of two LifeBlue batteries, and/or a smart alternator, you will need to use the Sterling Battery to Battery Charger. This keeps the charging current at a safe level and can be programmable for any battery chemistry. The Sterling Battery to Battery Charger can bring a battery up to 100% state of charge.
If you have a lithium battery system that can handle a charging current of 150A or more (three or more LifeBlue lithium batteries), and you do not have a smart alternator (here’s the Smart Alternator Test) you use the Victron Cyrix-Li-Ct battery combiner, variant “Lithium / 230A”. The Victron Cyrix-Li-Ct can quickly charge a lithium battery up to about 80% state of charge.
Neither device is needed if AGM batteries are used.
Estimated Installation Labor
Sterling Battery to Battery Charger
4 hours / $580
Enable DC/DC charging from your alternator to a secondary Lithium, AGM or Flooded battery bank. This kit is ideal for van conversions and skoolies with older alternators or lithium batteries with input current limits under 100A.
Ideal for: Vans, skoolies, motorhomes
*Please note that cables length needs may vary by application. Please email info@amsolar.com if you would like to customize the cable lengths to better suit your needs.
Victron Cyrix battery combiners connect your house battery bank to your starter battery and alternator to allow alternator charging. Additionally, when a charge is applied to a house battery bank the Cyrix will close and allow current to flow to the starter battery. Select an appropriate Cyrix based on your house battery type and alternator current rating.
Alternator 160A or less - 120A Cyrix
Alternator more than 160A - 230A Cyrix
3. Select solar charging system: Add a solar charging system that will fit on your roof. As a rough rule of thumb, every 100W of solar will produce about 25Ah (or 300Wh) of charge per day. If you have a solar pre-wire, check out section 3a of the Airstream page.
For a complete explanation of everything you would want to know about how to design a solar charging system, check out our Solar Charger Design Guide.
One of the most popular configurations for a Class C is two 200W solar panels on the 30A charge controller.
We recommend a minimum of 500W for any system with a residential refrigerator.
If you want to use a portable panel, we recommend oversizing the central charge controller so it can handle both the roof array and the portable panel.
The Victron SmartSolar MPPT charge controllers are compatible with any battery type, can work on 12V or 24V battery systems, and communicate status via Bluetooth.
Estimated Installation Labor
2x 200W on 30A Controller
12 hours / $1,740
Communicates battery voltage and solar charge rate to a smartphone or tablet via Bluetooth, Expandable up to 450W, Advanced MPPT charge controller delivers approximately 20% more energy than PWM, Combiner box covers roof penetration and allows for easy upgrades.
Communicates battery voltage and solar charge rate to a smartphone or tablet via Bluetooth, Expandable up to 700W, Advanced MPPT charge controller delivers approximately 20% more energy than PWM, Combiner box covers roof penetration and allows for easy upgrades, Panel(s) can be tilted
Solar Charging Kits and Components:
4. Select an Inverter/Charger System: The Victron Multiplus inverter/chargers combine an inverter and a charger in one unit. They also offer PowerAssist, which means that they can combine shore power with battery power when necessary. Our kits come with everything you need to upgrade your motorhome.
For a Class C Motorhome, you will want kit variants that include the phrase “RV Upgrade Kit”.
The 3000VA inverter/charger is only slightly more expensive than the 2000VA and shaped differently. The 3000VA inverter/charger gives you the option of running an air conditioner or running multiple appliances at the same time, like a coffee pot and a microwave. Installation time is the same for both inverters.
In order to fully support the 3000VA inverter, you will need a battery bank that can handle 300A of current outflow or three LifeBlue batteries. A 3000VA will work on a smaller battery bank, but will only work like a 2000VA inverter if only two batteries are used.
If you plan on running an air conditioner, you will need the 3000VA inverter system with an Easy Start kit. If you plan on running two air conditioners, consider a 24V system with a Victron Quattro 5000.
Estimated Installation Labor
Multiplus Inverter (RV Upgrade Kit)
17 hours / $2,465
The MultiPlus is a powerful true sine wave inverter, a sophisticated battery charger that features adaptive charge technology and a high-speed AC transfer switch in a single enclosure. Rated at 2000VA.
Note: Some Keurig coffee makers are known to be incompatible with inverters. In some cases, this will just result in a loud buzzing noise while operating, and in other cases, it will result in inverter overload and failure to operate. This doesn't mean your inverter will be damaged or that trying to use your coffee maker is dangerous; however, AM Solar cannot support compatibility issues resulting from a Keurig coffee maker. We recommend doing some research and purchasing a different coffee maker if you find yours to be incompatible with your inverter system.
Please note there is currently a nation-wide shortage of Duplex AC breakers (primarily 15/20). Our kits are designed to include these, but we may need to make substitutions due to stock level. Please email info@amsolar.com if you have any questions about this.
Steady State: 1600W
Surge: 4000W
Voltage Output: 120V AC
Voltage Input: 9.5-17V
No Load Draw: 3-9W
Waveform: Pure Sine
Frequency: 60hzCharger: 80A
Passthrough: 50A
Efficiency: 92%
Dimensions: H 19.70" x W 9.21" x D 5.75"
Extra: PowerAssist
The MultiPlus is a powerful true sine wave inverter, a sophisticated battery charger that features adaptive charge technology and a high-speed AC transfer switch in a single compact enclosure. Rated at 3000VA.
Note: Some Keurig coffee makers are known to be incompatible with inverters. In some cases, this will just result in a loud buzzing noise while operating, and in other cases, it will result in inverter overload and failure to operate. This doesn't mean your inverter will be damaged or that trying to use your coffee maker is dangerous; however, AM Solar cannot support compatibility issues resulting from a Keurig coffee maker. We recommend doing some research and purchasing a different coffee maker if you find yours to be incompatible with your inverter system.
If you have a 50A coach, we recommend looking into our MultiPlus-II 12/3000/2x 120V VE.Bus Inverter/Charger kits for 50A coaches.
Please note there is currently a nation-wide shortage of Duplex AC breakers (primarily 15/20). Our kits are designed to include these, but we may need to make substitutions due to stock level. Please email info@amsolar.com if you have any questions about this.
Steady State: 2400W
Surge: 6000W
Voltage Output: 120V AC
Voltage Input: 9.5-17V
No Load Draw: 8-20W
Waveform: Pure Sine
Frequency: 60hz
Charger: 120A
Passthrough: 50A
Efficiency: 93%
Dimensions: H 14.3" x W 10.2" x D 8.6"
Extra: PowerAssist
Inverter/Charger kits and components:
5. DC Distribution: This is only necessary if you are upgrading to a 24V battery bank, which would be very unusual in a Class C.
When using a 24V battery bank it is important to step down the voltage from 24V to 12V for DC loads.
Estimated Installation Labor
24V DC Distribution Kit
2 hours / $290
This kit includes everything you need to connect a 12V DC distribution block to a 24V battery system.
6. Optional components and tools: You may consider including these items in your purchase.
Tools - Make sure you have something equivalent to everything on the top row of this page.
Tech Support - Each kit comes with a set amount of free tech support, if you feel you may exceed that, you can purchase more here.